Method of and apparatus for making tubes of paper and the like



H. T. EPSTEIN June 17, 1947.

METHOD OF AND APPARATUS FOR MAKING TUBES OF PAPER AND THE LIKE Filld July 26, 1945 Harfyflpseff, y mm2/w# @www om. V4 vllnlluvuun I ratenteu June 17, 1947 METHOD 0F AND APPARATUS FOR MAKING TUBES OF PAPER AND THE LIKE Harry T. Epstein, Brookline, Mas-s.

Application July 26, 1945, Serial No. 607,199

This invention relates to improvements in methods of and apparatus for making tubes of paper and the like.

More particularly it relates to the making of straight, stiff tubes, consisting of two or more strips of paper or `other thin flexible material cemented together, each layer strip being curled transversely to cylindrical form so that its edges abut 'together in parallelism with the axis of the tube. The abutting edges are overlain by the body part of the next layer.

Tubes of this construction would be simpler and better than those made by winding paper strips helically, but, Where made by any method heretofore known, troubles arise which render the product commercially unsuccessful, including both defects in the product and difficulties in operation of the apparatus which increase the cost prohibitively. Important among these defects is failure to control the positioning of the edges, which should abut each other closely and smoothly, with no discernible gap. Previous methods leave the edges more or less upstanding, or slightly separated, or overlapping each other; or the tube may be ill-shaped. Also the apparatus previously proposed is subject to risk that in the absence of perfect control of the edges glue may smear its interior, making operative dilliculty.

It is one specic object of the present inven b tion to provide a method and apparatus by which to attain an adequate precision of abutting together of the two edges of each layer.

Another specific object is to provide a method and apparatus by which the cost is reduced, of commercially acceptable tubes, made of paper strips curled and laid with edges straight.

And it is the object of the invention, in general, to provide a, reliable method of dealing with the paper strips so as to combine them tightly and smoothly, by simple apparatus that can operate at high speed to convert flat strips of paper into a continuous tube.

The achieving of these objects endows the longitudinal-seam type of paper tube with industrial and commercial `advantages over all other types of paper tubes heretofore known to me. The method and the type of apparatus of the invention provide a continuous length of tube which can be sub-divided into Whatever lengths of individual tubes may be desired. Tubes of any diameter can be produced by the invention, and of any cross-sectional shape, although most uses will be served by the cylindrical shape herein illustratively shown. They can be made suitable for serving any of many different utilities; and they may be made of any of a wide variety of thin sheet materials, of which paper is typical.

One distinctive excellence of the invention beand cemented together in cylindrical layers.

Tubes having more than two layers can be made by adding layers successively, by the method and type of apparatus herein shown for adding the second layer to the rst. l,

The strip of paper or the like material which is to become a cylindrical or polygonal layer of the tube wall is rst cut to precisely the width which corresponds to its peripheral measure 'in the wall `when its opposite edges abut together in a straight line longitudinal of the tube. According to the invention the tube is to be formed with progress of this layer along a mandrel having the diameter of the interior of the finished tube. The natural resilience of the raw paper, when the strip is curled laterally, tends to make edges of the strip spring apart. The invention provides a step to reverse the resilience of the paper so that it tends to spring those edges toward a cylindrical form of somewhat less diameter than that which the inner layer of the tube wall is ultimately to have. This comprises a moistening to make the paper limp; a forming to the said smaller cylindrical shape; and a drying of the paper in that curve. Since the strip has a width equalling the circumference of its ultimate cylindrical size, the edges will at this stage be somewhat overlapped. The layer is curled to the said smaller diameter by a concave former of conventional type, around a section or stem of the mandrel having less than the full diameter; and the strip proceeds thence lengthwise of the mandrel, under draft by its forward finished portion, over a convex cone in the mandrel which gradually spreads the curl of the strip to the cylindrical form of finish size, in which the edges are abutting precisely, on the finishing cylinder of the mandrel, i. e. with no overlapping of the edges and no separation of the edges. Both edges hug this part of the mandrel closely, because of the acquired reverse resilience with which the paper strip presses them toward the smaller cylindrical size. The next stage is the adding of the strip which is to form the second layer of the tube wall, coated with liquid adhesive. This comes from the opposite side of the mandrel drawn by its forward portion which is already incorporated in the tube, through a concave former of conventional style which curls it from an initial flat cross section, in which it has become coated with glue, to a cylindrical cross section in which it surrounds the mandrel and first layer of paper, with its own edges abutting together. The forward part of its former is cylindrical and is of size to apply suitable pressure to cause adhesion of the second layer cylindrically to the rst layer as the two move along the mandrel into a heated region which dries and sets the adhesion. Thereby the tube becomes complete, reaches the end of the mandrel, and enters between a pair of rolls having frictional surfaces that grip and continuously draw the completed tube forward, to be severed into unit lengths by any suitable means. If additional layers, of the same sort or different sorts, are desired in the tube wall, these may be added one by one by the method used in applying the second layer to the first, using similar apparatus.

By reason of the reversal of resilience of the inner layer, and the effect of the cone of the mandrel in expanding the inner layer against that resilience, the edges of that layer lie close against the mandrel. Thus they are firmly in their final position when the second layer is applied. As they require no apparatus to restrain them from upstanding, there is nothing to inter'- fere with the precise laying of the second strip in, position to bind the edges of the inner strip in their closely abutting position, so that the two curled strips can be closely held between the former and the mandrel until the glue is dry.

It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty exist in the disclosure herein made.

In the accompanying drawing, which illustrates the invention by showing diagrammatically a product being made by the method and apparatus of the invention:

Figure l is a diagram illustrating both the method and the apparatus in vertical section close beside the axis, as on line i--i in Figure 5;

Figures 2, 3 and 4 are transverse sections through the partly formed tube and the apparatus at 2-2, 3---3,l and 4 4, respectively, enlarged;

Figure 5 is a transverse section at 5 5, Figure i further enlargedJ showing the nished double wall of tube as it leaves the apparatus;

Figure 6 is a side elevation partly in medial section of a straw as made by the invention;

Figure i is an end elevation of the straw of Figure 6, enlarged.

Referring to the drawings, Figures Eil and 7 represent a straw of the sort used for imbibing beverages, which, for illustration, may be assumed to have an interior diameter of one-eighth of an inch, comprising a tubular layer A and a tubular layer B, each of paper or other chosen material, bound together by a layer of glue C, the glue is represented by the double line in Figures 5 and '7, the scale of Figures l, 4 and 6, being too small for showing this element between the two layers that constitute the wall of the finished tube.

The mandrel i about which the tube is formed and finished extends from the middle to near the right hand end of Figure l, just before the section line *-5, its stem 9, of smaller diameter, being represented as held by and projecting from a bracket with set screw i2 at the left. The various steps of the process and elements of the apparatus occur around this stem and mandrel.

The inner layer. drawn by the finished part of the tube, which is drawn by the friction rolls l0, begins at the left as a fiat strip A; is moistened to limpness by a pan and roller i4; and while limp is curled laterally in the region of the stem 9, by a former i6, so that it has a transverse curvature slightly exceeding 360, as indicated in Figure 2. Beyond this a heater i8 in the region of the stem 9 dries the formed strip A in that shape and size. Resilience returns to the strip with the drying, and this resilience of the strip material tends to hold the strip in the shape in which it became dry. The drying occurs in the region i9 of the mandrel stem 9, which has less than the finish diameter. Beyond this stem the mandrel circumference becomes enlarged from what it was at I9, to the finish size, at 2|, which the strip A can surround with its edges precisely abutting, as seen in Figure 3. Between the stem at i9 and the nish size of the mandrel at 2i there is preferably a conical section 20, making a gradual expansion of the mandrel from stem 9 to body l0. If desired the cone can be omitted for, when the strip has been threaded through it passes naturally over the shoulder between stem and body. Being thus spread and put into a state of internal stress, the resilience of the paper stock presses the edges of the strip close to the mandrel, in the directions indicated by the little arrows in Figure 3.

The strip B, likewise drawn by rolls 30, receives at the pan and roller 24 a coating of a liquid adhesive, as glue C, whose place is indicated but whose thickness cannot well be shown in Figure l, and is exaggerated in Figures 5 and 7. The strip B carrying glue C enters the former l26 which curls it transversely, applies it to the exterior of the strip A on the mandrel, and holds these two strips suitably pressed between the former and the mandrel as they pass through a heater 28 for drying the glue. The tube thus completed passes off the end of the mandrel;becomes frictionally engaged by the pair of draft rolls 30, and thence is projected as a continuous finished tubular product.

The formers I6, 26 may be of any conventional type, those which are represented being split blocks having interior surfaces that are suitably curved for guiding the strips from flatness to cylindricality.

If an adhering substance is used which requires no drying, or if it is desired to complete the adhering by simple drying in air, the second dryer, 28, may be omitted.

The moisteners, I4, 24, iormers, I6, 26, and heaters i8, 28, and draft rolls 3D, may be of conventional type, suitably shaped and arranged. The strip A has a width predetermined as being exactly proper for making the edges of the inner layer ultimately abut each other when closely formed about the larger part of the mandrel lli. The strip approaches the smaller diameter region I9 of the mandrel from the underside. The former i6 makes its edges come together on the upper side, and overlap slightly; and hold them in this position while the paper is acquiring resilience by the drying effect of the heater IB. Thereafter, the conical enlargement of the mandrel diminishes the overlap of these edges until as the greater diameter of the mandrel is reached the upper lap springs in, to stand with both edges at the same radial distance from the axis, both hugging the mandrel in perfect position to receive the precisely-dimensioned glue-coated strip diameter; means for B, which the former 26 make the edges of the strip B abut each other underneath the layer A. The two layers thus held together on the mandrel become firmly adhered together in the drying region of the heater 28. rI'he rolls 30 may have surfaces of rubber or other material suited to grip and draw the tube. Thus the tube is made by continuous operation and in continuous length, 'to be cut into such sectional lengths as may be desired, as, for example, for use as soda straws.

Using larger dimensions of apparatus, and of strips, tubes of larger size and of other materials may be made for other purposes, as, for example, for the bodies of paper cups and cans; for bobbins, roller tubes, mailing tubes, and whatever may be desired.

The invention thus makes it possible to produce layered tubes, with staggered longitudinal seams in which the edges abut so closely that the exterior of the tube is smoothly circular; and the shapes around it so as to ,y tually abutting method of construction permits a speed of output f which is markedly improved over competing methods and apparatus, with substantial reduction in the cost of the product.

I claim as my invention:

1. A method for making a tube having a plurallayered wall of iiat strips of paper or like material curled transversely with straight longitudinal seams, characterized in that it includes the steps of moistening to limpness a rst strip whose width equals the circumference of the inmost layer of the tube wall that is to be made, and, while that strip is limp, curling it to tubular form with its edges mutually overlapping; drying it so; then expanding that form until the edges abut each other; then curling a` second strip around the iirst and applying it thereto with an adhesive substance intervening, this second strip covering the abutting edges of the first strip.

2. A method for making a tube having a plurallayered wall of iiat strips of paper or like material curled transversely with straight longitudinal seams, characterized in that it includes the steps of reversing the direction of the resilience of the stock of a ilrst strip, from a resilience towards flatness to a resilience toward a curled formation having greater curvature than is the curvature of the inmost layer of the tube wall which is to be made; spreading the strip against this reversed resiliencc until the edges of the strip abut together; curling and adhering to the first strip a second strip exteriorly coveringy the abutting edges of the iirst strip; thus constituting a tube having a plural layered wall.

3. Apparatus for making a tube having a plural-layered wall of dat strips of paper or like material curled transversely with straight longitudinal seams, comprising in combination a mandrel having a region with cross section equalling that which the interior surface oi.' the nished tube is to have, and have a stem region of less drawing the finished tube and its component materials along the mandrel ,whose inmost wall is from the region of less diameter during the making of the tube; means adjacent to the stem region for moistening to limpness a fiat strip of stock having width equalling the circumference of the inmost layer of the tube which is to be made and finished; means, in the said region of less diameter, for curling that strip to more than 360 While it is limp, and for drying this strip thus curled; the mandrels region of finish diameter being subsequent in the direction of draft, with adjacent means for curling and applying an adhesive second strip of stock with its edges muat a peripheral distance from the edges of the iirst strip.

4. Apparatus as in claim 3, further character` ized in that there is in the mandrel a region ofi,

gradually expanding surface connecting the region of less diameter with the region of iinish diameter, for expanding the-.dried curled strip.

5. Apparatus for making a plural-walled tube whose inmost wall is a longstrip of paper or the like material curled with its edges butted together longitudinally of the tube, comprising a mandrel, whose diameter fits the finished tube, combined with a mandrel of smaller diameter; means for curling the strip around the smaller mandrel with edges of the strip extending longitudinally of the mandrel, and overlapping each other; means setting the strip material with its resilience tending against displacement from said overlapping; said mandrel of nish diameter pro- Viding means displaced to abutting position; and means to apply an outer wall, covering the strip ,edges While they are thus held in abutting relation on `the nish mandrel.

6. Apparatus for making a plural-Walled tube a long strip of paper or the like material curled with its edges butted together longitudinally of the tube, comprising means to curl a iiat strip of the material to tubular form with its edges extending longitudinally of the tube, and overlapping each other, and means setting the material with its resilience tending against displacement from said overlapping, combined with a mandrel whose diameter ts the interior of the edges are displaced to mutually abutting position; and means to apply to the curled tube thereon an outer wall covering the abutting strip edges.

HARRY T. EPS'IEIN.

REFERENoEs CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS for holding-the strip with its edges strip tube when its said 

